The use of elongated rails to guide or support people conveying vehicles is well known. The rails are typically fixed in a supported structure or on grade, with a series of suspended rollers or wheels placed between the moving vehicle and the fixed rail.
For elevator applications, there are typically two rails disposed on opposite lateral sides of the elevator car and running the entire length of the elevator hoistway. The elevator car, typically suspended by steel ropes from the upper end of the hoistway, or by an hydraulic piston disposed at the hoistway bottom, is guided and centered by the rails as it traverses the hoistway. As will be appreciated by those skilled in the art, any deviation or nonlinearity in the rails will cause the traveling elevator to sway or vibrate as it traverses the nonlinear sections.
A time consuming task during new elevator installations, as well as elevator modernization, is the surveying and straightening of rails which may have been improperly aligned during the installation process, or become misaligned over time due to building settling or other reasons. The misalignment problem is particularly vexing in high rise buildings which typically have high speed elevators and extremely long rails.
The prior art methods of aligning elevator guide rails include the use of one or more wires stretched from the top to the bottom of the hoistway, or a laser beam affixed at one end of the hoistway and directed so as to project adjacent the subject guide rail. In each case, workers traverse the elevator hoistway measuring the position of the guide rail relative to the stretched wire or laser beam in an attempt to accurately determine the position of the rail and any deviations from linearity along its length. As will be appreciated, such procedures are extremely time consuming requiring not only the set up of the laser or wire reference, but also potentially hundreds of painstaking measurements along the guide rail.
An additional complication relates to the nature of high-rise buildings which are, by design, subject to swaying under the influence of wind loading or other live building loads. It is, therefore, common practice to conduct surveys of elevator rails at night when the building is unoccupied and during periods of little or no exterior wind. For measurements using a stretched wire as a reference, it will be appreciated that should the wire be struck inadvertently or moved by air currents during the process, there may be a need to wait until any vibrational movement in the wire has decayed before continuing the rail survey.
Finally, upon completing the survey, workers must then determine which sections along the rail have become misaligned and attempt to reduce or eliminate the misalignment. Guide rails are typically assembled from individual rail segments jointed end-to-end by overlapping fishplates, and supported against the walls of the hoistway by mounting brackets. For misalignments occurring at the segments joints, workers may shim and rebolt the fishplates or grind any protruding segment ends so as to smooth the transition between adjacent segments. For other misalignments, workers may attempt to loosen the mounting bracket, move the rail accordingly, and resecure the rail in the correct position. Upon completion of the realignment, it is then necessary to again survey the rails to determine if the realignment has been successful.
What is needed is a method and apparatus for reducing the time required to survey an elevator guide rail which is not affected by concurrent building use or external weather conditions.